Electromagnetic contactor



Aug. 18, 1970 I I r}. M. SCHRAMM ET AL 3,525,059

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'1 W Ha Aug. 18, 1970 R; M. SCHRAMM ET AL 3,525,059

ELECTROMAGNETIC CONTACTOR 4 Sheets-Sheet L- Filed May 6, 1968 INVENTORS. SCHRAMM ROBERT M. CHARLES ALLA/V SCHURI? JA/VEZ SEVE/P Au..1s,191o' Mammy-HAL 3,52 ,059

ELECTROMAGNETIC CONTACTOR Filed ma 6, 1968 4v Sheets-$heet 5 n "I a. was :0

l/VVE/VTORS. ROBERT M. SCHRAMM CHARLES ALLA/V SCHURR -JANEZ F SEVER Q L Hi-EL. 5.

Aug. 18, 1970 R. M. SCHRAMM ET AL 3,525,059

ELECTROMAGNETIC CONTACTOR 4 Sheets-Sheet L Filed May 6, 1968 "VI/ENRQRS. ROBERT/W. SCHRAMM CHARLES ALLA/V SCHURR JANEZ .F SEVER B) W United States Patent 3,525,059 ELECTROMAGNETIC CONTACTOR Robert M. Schramm, Maple Heights, Charles Allan Schurr, Shaker Heights, and Janez F. Sever, Cleveland, Ohio, assignors to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed May 6, 1968, Ser. No. 726,722 Int. Cl. H0111 50/16 US. Cl. 335-132 9 Claims ABSTRACT OF THE DISCLOSURE A clapper-type electromagnetic contactor which may be assembled as either a normally-open or a normallyclosed device from substantially the same set of components. Once assembled, the contactor may be converted from normally-open to normally-closed, or vice versa, by changing the relative positions of certain components and substituting only a few others.

This invention relates to an electromagnetically-operated clapper-type contactor the armature of which is spring-biased toward one position and magnetically moved to another position for controlling electric contacts by the armature movement. More particularly, the invention relates to such a contactor which may be assembled in either a normally-open or a normally-closed arrangement from substantially the same set of components, and which, once assembled, may be readily converted from normallyopen to normally-closed, or vice versa, principally by changing the relative positions of certain components in the assembly.

Both normally-open and normally-closed electromagnetic relays and contactors have long been provided for use in electrical circuitry. Likewise, it is well known in the art to provide small relays and contactors of relatively low power rating with reversible contacts or the like for converting the devices from normally-open to normallyclosed configurations, and vice versa. In heavy duty. or mill type contactors of the prior art capable of repeatedly switching circuits carrying fifty amperes or more, conversion from normally-open to normally-closed configuration is not readily accomplishable and, generally, separate families of such normally-open and normally-closed contactors have been provided. Although the prior normally-open and normally-closed heavy duty contactors do have certain parts in common with each other, the differences in construction and in the components employed in the separate devices render it impractical and relatively difiicult to convert from one configuration to the other.

The contactor of the present invention makes it possible to accomplish such conversion with relative ease by interchanging the location of certain principal components of the contactor and by substitution of a few minor components. Accordingly, the present invention enables contactors to be assembled in either a normally-open or normallyclosed configuration from a relatively small inventory of parts.

A principal object of the present invention is to provide an electromagnetically-operated clapper-type heavy duty contactor which may be assembled in either a normallyopen or normally-closed arrangement from substantially the same set of components with relative ease.

Another object is to provide an electromagneticallyoperated clapper-type heavy-duty contactor which, once assembled, may be readily changed from normally-open to normally-closed configuration principally by changing the relative positions of certain components in the assembly.

Other objects and advantages will become apparent ice from the following specification wherein reference is made to the drawings, in which:

FIG. 1 is a perspective view of an electromagnetic contactor in accordance with this invention, the contactor being assembled for a normally-open mode of operation;

FIG. 2 is a side view of the contactor assembled as in FIG. 1, a portion of an arc chute of the contactor being broken away to illustrate additional detail;

FIG. 3 is a side view similar to that of FIG. 2, but with the contactor assembled for a normally-closed mode of operation and with its arc chute removed;

FIG. 4 is an exploded perspective view of a portion of the contactor arranged for the normally-open mode of operation as in FIGS. 1 and 2;

FIG. 5 is an exploded perspective view of a portion of the contactor arranged for the normally-closed mode of operation as in FIG. 3;

FIG. 6 is a front view of the contactor assembled as in FIGS. 1 and 2, a portion of the arc chute being broken away for clarity of illustration; and

FIGS. 7 and 8 show additional details of the contactor.

Referring first to FIGS. 1 and 2 of the drawings, an electro-magnetic contactor in accordance with this invention comprises a base 10 having means such as upper and lower slots 10a by which the contactor may be mounted upon a control panel. Preferably, the base 10 is molded of a strong, electrically insulative material such as glass-reinforced polyester.

As shown in FIGS. 1, 2, and 4 an operating assembly 11 of the contactor comprises a magnet frame 12 having two leg portions disposed generally at right angles to each other, an operating winding or coil 14, a cylindrical core 15, an armature 16, and a contact arm 17. The magnet frame 12 and the core 15 are secured to the base 10 against a flat mounting surface 10a thereof by a screw 19 which is received, through aligned openings in the base and one of the leg portions of the magnet frame, in a threaded axial socket in the core 15. Thus, one leg portion of the magnet frame 12 serves as a mounting leg portion for mounting the frame 12 on the base 10. The coil 14, comprising a winding encapsulated in an insulating material such as epoxy or the like, has an axial opening extending therethrough and also has a pair of terminals 14a adapted for connection to a source of power for energizing the coil.

The coil 14 is received on the core 15 where it is retained in place by a core cap 20 which is secured to the core 15 by a screw 21. A thin non-magnetic spacer (not shown) may be placed adjacent the core cap 20 under the head of the screw 21. A spring washer 22, disposed between the coil 14 and the mounting leg portion of the frame 12, urges the coil firmly against the core cap 20.

The contact arm 17, also preferably molded of a strong insulative material such as glass-reinforced polyester, is pivotall retained on the magnet frame 12 by a pin 23 which is received through respective pairs of aligned openings 25 and 26 (FIG. 4) in the arm 17 and in the ears of a U-shaped depending bracket 27 welded to the other leg portion of the magnet frame 12. The pin 23 is restrained against axial movement by means of a spring member 24 (FIGS. 7 and 8) having an end portion 24a which is seated in and resiliently bears against a narrowed neck portion 23a of the pin 23. The member 24 is itself removably secured to the bracket 27 by a clip-like portion 24b which is slidably received about a shallow raised section of the bracket 27. A small tang 27a raised from the bracket 27 is received in an opening 240 of the spring member 24 to assist in retaining the member 24 securely on the bracket 27.

The armature 16, best illustrated in FIG. 4, is a flat, generally rectangular steel plate member and is secured to the contact arm 17 by a pair of screws 28 threaded into respective holes in the armature through openings 17a in the contact arm. Thus, the armature 16 is carried by the contact arm and is adapted for pivotal movement therewith toward and away from the coil 14 between respective closed and open positions. A return spring 29 (FIG. 2) disposed between the core cap 20 and the contact arm 17, and retained at one end about the head of the screw 21 and seated at its other end in an opening in the armature 16, assists the forces of gravity in returning the contact arm to its open position. The contact arm 17 carries, in addition, an auxiliary arm 30 which is pivotally mounted on the contact arm as by means of a pin 31 passing through aligned openings in spaced ears 30a of the arm 30. A spring member (not shown) like the member 24 constrains the pin 31 against axial movement. A helical spring 32 biases the auxiliary arm 30 in a counterclockwise direction about its pivotal axis as viewed in FIG. 2. Like the contact arm 17, the auxiliary arm 30 is preferably molded of glass-reinforced polyester. A stop plate 33, mounted on the base by bolt and nut fasteners 34, has a distal end portion 33a which lies in the path of movement of, and cooperates with, the auxiliary arm 30 to determine the open position of the contact arm 17.

Mounted on the auxiliary arm 30 by means of a cap screw 35 are a contact tip 36 (designated the movable contact), an arc horn 37, and one end of a flexible connector 38. The other end of the flexible connector 38 is fastened, as best illustrated in FIG. 6, to a terminal block 39 by a screw 40- which also secures the terminal block to the base 10. The flexible connector 38 completes an electrical circuit between the movable contact 36 and the terminal block 39, and the terminal block has lug portions 39a which are drilled and tapped so as to facilitate the attachment of terminal lugs of one or more electrical leads (not shown) of the circuit which is to be controlled by operation of the contractor.

Electrical connection from the circuit to be controlled to a stationary contact 41 of the contactor is provided through a terminal block 42 disposed at an upper end portion of the base 10 and having lug portions 42a similar to the lug portions 39a of the block 39. A blowout coil 44, comprising a multi-turn coil of edgewound copper conductor, completes the electrical circuit between the terminal block 42 and the stationary contact 41, one end 44a of the blowout coil 44 being connected to the lug portion 42a of the terminal block 42 by a screw 45 (FIGS. 1 and 6). A screw 46 (FIGS. 2 and 3) secures the other end 4411 of the blowout coil 44, together with the stationary contact 41, to the base 10. Thus, when the movable and stationary contacts 36 and 41 are in engagement with each other, a complete circuit extends from the terminal block 42, through the blowout coil 44, the stationary contact 41, the movable contact 36, and the flexible connector 38 to the terminal block 39.

As is customary in the art, the blowout coil 44 is disposed between and in flux-linking arrangement with a pair of blowout cars 49, the cars 49 being fastened in spaced relation to the blowout coil 44 by a pair of screws 50 to opposite end faces of an insulated cylindrical flux-conducting core (not shown) disposed coaxially within the blowout coil 44. As illustrated in FIG. 2, the blowout ears 49 are so disposed with respect to the contacts 36 and 41 as to concentrate the flux produced by the blowout coil across the gap between the contacts 36 and 41.

An electrically conductive non-magnetic arc runner 51 (FIGS. 2, 3 and 6), preferably formed of copper, has one of its ends disposed beneath and in electrical contact with the stationary contact 41. The other end of the runner 51 is supported in a recess in the base 10 and is retained therein by means of a projection 52 of the base 10 which cooperates with a shallow bend in the runner 51 so as to prevent withdrawal of the runner when its one end is secured in position beneath the contact 41.

To assist in confining and extinguishing arcs formed upon separation of the contacts 36 and 41, the contactor is provided with a removable arc chute 54. While the arc chute may take any one of the many forms well known in the arc, the preferred embodiment of the arc chute 54 comprises two complementary portions, molded of suitable arc-suppressing material, which are secured to each other in assembled relationship by fastening means such as tubular threaded stud and screw fasteners 55. Although not illustrated in the drawings, the arc chute 54 is provided with conventional internal baffies which assist in extinguishing the are.

In order to assist in removably retaining the arc chute 54 on the contactor, an upwardly struck tang portion 51a of the arc runner 51 cooperates with an internal shoulder portion 56 (FIG. 2) of the chute 54 to prevent movement of the arc chute in a direction normal to, and away from, the front-face of the base 10. Likewise, shoulders 57, defined by a recessed portion on the exterior of each of the complementary portions of the arc chute 54, cooperate respectively with the upper edges of the blowout cars 49, as shown in FIG. 1, to support the chute 54 on the contactor. In addition, a pair of resilient members 59, secured beneath the screws 50, respectively, and having offset end portions, cooperate with grooves in the arc chute 54 to assist in retaining the chute in place. Thus, although the arc chute 54 is securely retained on the contactor, it may be removed therefrom at will merely by withdrawing it in an upward direction out of engagement with the tang portion 51a of the arc runner 51.

One of the principal features of the present invention resides in that the contactor may be changed from the normally-open device shown in FIGS. 1, 2, and 4 to a normally-closed device as shown in FIGS. 3 and 5 by re-arranging the principal parts and by substitution or addition of a small number of other components. This feature enables either a normally-open or a normallyclosed version of the same basic contactor to be manufactured from a relatively small inventory of parts. Also, once assembled, the contactor can be changed, if necessary, from one mode of operation to the other with relative ease.

The manner of assembly of the contactor of this invention as either a normally-closed or normally-open device, or the manner of changing the same from one version to the other, is best illustrated in FIGS. 4 and 5 of the drawings. As is evident from a comparison of these two figures, the change from the normally-open to the normally-closed configuration is accomplished substantially by re-arranging and interchanging components of the operating assembly 11. The base 10 and its associated blowout coil 44, stationary contact 41 and are chute 54, and the magnet frame 12, armature 16, and contact arm 17 are common to both configurations. Substitution of components is required only for the operating coil 14, the core 15 and its associated core cap 20 and spacer, the spring 29, and the stop plate 33.

In the normally-open arrangement, shown in exploded view in FIG. 4, the mounting leg portion of the magnet frame 12 is disposed parallel to and abuts the mounting surface 10a of the base 10 as previously described, with the edge 12a of the magnet frame 12 positioned adjacent to and in abutting relationship with a shoulder 10b on the base. Also, as previously described, the armature 16 is retained on the contact arm 17 by the screws 28 received through the openings 17a.

In the normally-closed arrangement, illustrated in exploded view in FIG. 5, the magnet frame 12 is repositioned with respect to the base 10 so that it is disposed on the base with its mounting leg portion normal to the surface 101; and with its edge 12a positioned adjacent a shoulder of a supporting projection 10 which is molded integrally with and extends normal to the plane of the base 10. In this position, the mounting leg portion of the frame 12 is disposed in abutting relationship with a mounting surface on the underside of the projection 10 which surface is disposed normal to the mounting surface a. A pair of screws 60 secures the frame 12 to the contactor base 10. The cooperation of the edge 12a with the shoulder 10b in the normally-open configuration of the contactor, and with the shoulder 100 in the normallyclosed configuration, assures that the magnet frame 12 will be in proper alignment when it is secured to the base 10 in either configuration.

In the normally-closed arrangement, the armature 16 is retained on the contact arm 17 by screws 61 threaded into the armature through openings 17b which are located at the opposite side of the pivotal axis of the contact arm from the openings 17a. A stop plate 62 (FIG. 3) is secured to the contact arm 17 by screws 63 which are received in threaded holes in the stop plate through the openings 17a.

Thus, as is evident from a comparison of FIGS. 2 and 3, the contacts 36 and 41 in the normally-open arrangement of FIG. 2 are closed, upon energization of the coil 14, by the forces of electromagnetic attraction between the core and the armature 16. The contacts 36 and 41 are opened, upon deenergization of the coil 14, by the force of gravity assisted by the spring 29 and, in the initial stage of movement, by the spring 32. Conversely, in the normally-closed arrangement of FIG. 3, the contacts 36 and 41 are urged to their closed position by the force of a closing spring 64 and are caused to open upon energization of a coil 65.

In the normally-closed arrangement, the spring 64 must of itself provide sufficient force to positively maintain the contacts 36 and 41 in their normally-closed position. Accordingly, the spring '64 of the normally-closed arrangement is selected so that it applies a greater force than that of the spring 29 in the normally-open configuration which only assists in opening the contacts. As a consequence of the greater force provided by the spring 64 in the normally-closed contactor, the coil 65 for the normally-closed arrangement is likewise selected so that it will, when energized, provide sufficient electromagnetic force to compress the spring 64 and effect a quick and positive opening of the contacts. In order to accommodate a spring of increased spring rate, a core 66 for the normally-closed arrangement of the contactor has an axial bore so as to permit a spring of increased length to be employed. Additionally, in order to provide the desired magnetic pull characteristics to assure rapid separation of the contacts 36 and 41, a magnetic core cap 67 of generally rectangular configuration and having a bent flange portion 67a is provided in place of the core cap 20. However, neither the substitution of the springs, the coils, nor the cores and associated core caps detracts materially from the ease of convertibility of the contactor from normally-open to normally-closed configuration, or vice versa, inasmuch as these components are dimensioned so as to permit ready interchangeability in the basic contactor assembly.

We claim:

1. An electromagnetic contactor including a base, a magnetic frame, means for mounting said frame selectively in either of two positions on said base, a movable contact arm supported for to and fro pivotal movement with respect to said base, an armature, means for supporting said armature on said contact arm selectively at either side of the pivotal axis of said contact arm, said armature being supported at one side of said pivotal axis when said frame is mounted on said base in one of said two positions, and said armature being supported at the other side of said pivotal axis when said frame is mounted on said base in the other of said two positions.

2. A contactor in accordance with claim 1 wherein said frame has two leg portions disposed at right angles to each other, one of the leg portions comprises a mounting leg portion for mounting said frame on said base, said means for mounting said frame on said base comprises first and second mounting surfaces on said base for mounting said mounting leg portions thereon, selectively, said first and second mounting surfaces being normal to each other, and said mounting leg portion is secured to said first mounting surface in said one of said two positions and is secured to said second mounting surface in said other of said two positions.

3. A contactor in accordance with claim 2 and additionally including a flux-conductive core supported at one endon said mounting leg portion of said frame in fluxconducting relationship therewith and extending generally parallel to the other of said leg portions, and a coil coaxially surrounding said core, whereby the longitudinal axis of said coil and core extends generally parallel to said second mounting surface when said frame is mounted on said base in said one of said two positions and extends generally parallel to said first mounting surface when said frame is mounted on said base in said other of said two positions.

4. A contactor in accordance with claim 2 wherein said contact arm is pivotally carried by the free end portion of the other of said leg portions.

5. A contactor in accordance with claim 4 wherein a pin is provided for pivotally supporting the contact arm and has a narrowed neck portion disposed between its respective end portions, and wherein a spring member is provided having a portion which is seated in and resiliently bears against the neck portion of the pin so as to restrain the pin against movement in an axial direction.

6. A contactor in accordance with claim 1 wherein a flux-conductive core is supported at one end on said frame in flux-conducting relationship therewith, said armature moves toward and away from the other end of said core as said contact arm pivots to and fro, a stationary contact is supported by said base, a movable contact is carried by said contact arm and is movable therewith between first and second positions with respect to the stationary contact as said contact arm pivots to and fro, and biasing means biases said contact arm so as to urge said armature away from said core, thereby to urge the movable contact to its first position when said frame is mounted on the base in said one of said two positions and said armature is supported at said one side of the pivotal axis, and to urge the movable contact to its second position when said frame is mounted on the base in said other of said two positions and said armature is supported at said other side of the pivotal axis.

7. A contactor in accordance with claim 6 wherein an electrically energizable coil is provided for moving the movable contact between its first and second positions against the force of said biasing means.

8. A contactor in accordance with claim 1 wherein a flux-conductive core is supported at one end on said frame in flux-conducting relationship therewith, said armature moves toward and away from the other end of said core as said contact arm pivots to and fro, a stationary contact is supported by said base, a movable contact is carried by said contact arm and is movable therewith between open and closed positions with respect to the stationary contact as said contact arm pivots to and fro, and biasing means biases said contact arm so as to urge said armature away from said core, thereby to urge the movable contact to its open position when said armature is supported on the contact arm on the same side of the pivotal axis as said movable contact, and to urge the movable contact to its closed position when said armature is supported on the contact arm at the opposite side of the pivotal axis from said movable contact.

9. In an electromagnetic contactor including a base, a stationary contact supported by said base, a magnetic frame, a flux-conductive core supported at one end in flux-conducting relationship with said frame, an electrically energizable operating winding surrounding said core, a movable contact arm pivotally supported for to and fro pivotal movement with respect to said base, an armature on said contact arm movable toward and away from the other end of said core as said contact arm pivots to and fro, said armature being responsive to energization of said operating winding to cause said to and fro pivotal movement, a movable contact supported on said contact arm and movable therewith toward and away from said stationary contact as said arm pivots to and fro, and biasing means biasing said armature away from said core, the improvement comprising means on said contact arm for receiving said armature, selectively, in either of two positions, and means on said base for receiving said frame, selectively, in either of two positions, the contactor being so constructed and arranged that when said frame and said armature are disposed on said base and said arm, respectively, in one of their respective positions, the contactor is in a normally-open configuration, and when said 15 References Cited UNITED STATES PATENTS 7/1959 Wood 335132 6/1968 Isler 335-132 10 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner US. Cl. X.R. 335-198 

